この単純なPHPフォームを機能させる方法がわかりません。私は何が間違っていますか?
<?php
$first = "firstNumber";
$second = "secondNumber";
$second * $first = "calc";
$calc = "calc";
echo("" . $_GET['$calc'] . "<br />\n");
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<form action="new.php" method="get">
<input type="text" name="firstNumber" id="first">
<input type="text" name="secondNumber" id="second">
<input style="background-color: #0094ff;" type="submit" name="calc" value="שלח" id="second">
</form>
</body>
</html>